Image-modifying apparatus for photography



Nov. 13, 1928. 1,691,366

A. AMES, -JR

IMAGE MODIFYING APPARATUS FOR PHOTOGRAPHY 'original Filed Jan. 1v, 1920 v1 X f3 sf 7" f//l//l/l//l//ll/p/ 7/// 27 l8 /6 K0 24 8 32, 36 J0 44 48 d2 56 l@I0 64 I Il.: la, f y OM y @2m CM @WM 'Maar/g.

` The natural objectsfare tr Vthe photograph must Patented Nov. is, 192s.

UNITED STATES PATENT carries ADELBERT AMES, JR., OF HANOVER, NEW HAMPSHIRE.

IMAGE-MODIFYING APPARATUS ron PHOTOGRAPHY.

Continuation of application Serial No 351,012. filed January 1"?, 1920.* Ths application led June 1,

' 1923, Serial No.-642,754. i

the ii'nagination, as a reproduction of the objects depicted.

At best, photographsr are limited to a partial presentmlon.onlyot the factors or qualities giving distinguishing appearance to natural objects as viewed by the human eye.

be lviewed as a plane projection, either as thrown upona screen, as a. transparency seen against an illuminated background, or as an arrangement of light and dark places on a paper or other surface. The complete illusion'ot looking at the object pictured is not reached by any photograph because-ofthe artiticialit-y ot the picture due to these-reasons. Absence ot color is ot course also a factor in failure ot illusion, but not the most important factor. s Y

The present invention has todo with the simulation ot the sensitiveness of the retinal f surface of the eye, especially in respect to stimulation by color.k .Discovery by research shows a i iarked selective distribution ot sensitivity to color ot the human eye, and I shall herein describe contributions to the art tor the purpose ot causing photographic pictures to conform, whether monochromatic or polychromatic, to the appearance expected by the normal eye in respect to the value ol representations ot differently colored objects, especially in respect to the position of the object in the line ot sight or center ot' interest, or elsewhere at an angle to this line of sight, in the object field. y

One aspect of my invention is particularly applicable tothe making of monochromatic component pictures tor selective color by superposition ot differently colored 'monochromes, thus making polychromatic photographs 4in the colors ot nature. of theinvention is to provide means for securing a variable sensitiveness of the plate with respect to a colored impression while maintaininguniformity or other predetermined distribution of degree oit sensitiveness in a quantitative sense upon the plate in relation to its axial center and angular regions.

i-dimensional, but

. One object 'ln the accon'xpanying drawings Figure l is a'diagram in plan illustrating central areas ot the completed photograph and `of selective screens employed between the plate and the photographic lens;

Figure 2 is a section onany radius from the center of Fig. l, illustrating a typical arrangement according to the invention;

Figure 3 is a diagram illustrating quantitatively the distribution ot intensitieso't perception of light ot different wavelengths or colors in respect to the retina ot the. normal eye, and also showing the distribution of intensities of perception at low illuminations; andV 1 f Figure fl is a section similar to Figure 2 illustrating a modified form of the device ot' the invention. e

Referring tothe drawings, photographs made with the aid of the apparatus are positive or negative projections, transparencies or prints produced by any preferred process roma negative A, Fig; 2, which may comprise anyA preferred sensitive emulsion coating con any kind of backing b such as the iiat glass plate indicated, when suitably exposed and developed. y

For the lparticular purposes of this inven-` tion, the coating@ should approach the color sensitivity ot the eye, so far as average relative degree Aof chemical sensitiveness to light ot different wave-lengths is concerned. A .commercial panchromatic plate having sensitiveness inthe yellow light near the sodium D lines, yan intra-red limit at about the A lines, and low scnsitiveness to Wave lengths shorter than the Gr lines, is satisfactory tor the y purpose intended. The well-known lVratten panchromatic plate, for instance, is a suitable plate. Y

'It such a plate is exposed in the image plane ot a photographic lens system (prefer,- ably a lens system having the aberrations, diffusions and distortions characteristic o't the human eye), its reaction to the luminous A intensities of the image' will be uniform .throughout theiexposed surface of the plate.

-grees of thevisual angle.

certain peculiarities of the'eye "Withfrespectf to perception of color. y

Referring now to Figs. l and 3, the clearest seeing part of the retina, the tovea centralis7 is concentrated on a surface about one degree ot are Wide, situated nearly centrally ot' the so called yellow spot, having an oval area about G degreesu'ide in a horizontal direction, and about-t degrees Wide in a vertical direction, and these areas ot' the. retina are abo-ut centrally ysituated in a region of Y sensitivcness substantially `Je() degrees, more or less, Wide (all as measured from the nodal point of the ocular lens), otless sensitlvity than thel yelloiv spot. The outside .part otA y the last mentioned region is sensitive in'lesscned degrees to something lbeyond 40 de- These different regions oi' the eye vary substantially in respect to their power of excitation by light of different colors. The result of a careful series or' measurements in these particulars is plotted in VFig. 3.

In this figure the various tracesshow by their ordinates percentages of intensity of visual perception of the bright continuous spectrum from the cathode crater of a carbon Vare light at respective'rcgions of the retina,

the Wave-lengths being indicated according to an arbitrary scale by the abscissze. The following table ot' mean readings ot these 'quantities by observation ot' a number vof individual and normal eyes gives the data Which the figure graphically shows:

' Outside l x Wave Y Yellow Fovea Soak numb length yuo spot centrals pot 7217 7082 1 6957 14 2 2 6829 2 4 4 6728 34 5 7 8 6G21 7. 12. 5 15. 5 6520 12.5 21 24 (i423 19 33 37.5 6330 27.5 60 6242 l 35 65 77 6152 `43' 80 90 6074 52.5 90 97 5996 61 96 1GO 5919 71 y 9s 10o 5850 79 100 98 5773 r84 ,99 95 5720 S5 9T 90 5658 83. 5 92. 5 S5' 5596 81 87 'T9 5538 77 81 72.5 5181 72.5 (J6 5127 .(18 G0 59 5373 62.5 62.5 51 51121l 57 57 45 5270 52 50 4() 5221 4G 42.5 32 5172 41.5 36 27.5 5128 37. 5 29.5 22 5085 33.5 24 153 5043 30 13. 2 14 5002 26. 5 14. 2 10 Outside yellow Ye11ow Fovea It will be observed that the maximum `intensity at the fovea centralis is in the yellow light between vWave-lengths k=`5919a and /\=5996,a; that the equivalent lmaximum `for theyellow spot is a1 i\=`5850,a-and-that the Visual intensity of the same light on `the surrounding region 10o from the ovea is only about 85% ot' that for the fovea and yellow spot and maximum at aboutv a=5720/i; but that this region exceeds the yellowspot and ovea in sensitiveness tothe greens and blues extending from /\=5270,a to the ultra-violet Visual limit.

It these values are determined in low 4.illuminations, the normal eye undergoes not only pupillary expansion, but also changesits selective color sensitivity. The saine spectrum When'reduced in intensity-to the photometric value at theD lines ot 1/1325 of theillu-mination by a standard amyl lamp ata distance of one toot affects the retina according to the M can Wave length reduced to 100 f maximum Scale number reading Thek maximum perceptive intensityl under these circumstances shifts intothe green at about =5270a, the perception of longer wave-lengths being rmarkedly inhibited and of shorter Wave-lengths markedly increased.

It will now be apparent that an illusive photograph giving either a correct monochromatic translation of panchromatic values, or comprising a polychromatie composite of monochrome elements, should faithfully record the different values of the image perceivedat the center of interest (by the fovea) at the region near by (by the yellow spot) and at the outlying parts of the visual angle (by the remainder of the retina).

W'hatever the photographic means employed, a plate uniformly sensitive to color and uniformly exposed to the image in a camera can not comply with these conditions.`

This invention therefore comprises a rgenus of new devices enabling the plate to record variably in a chromatic sense the image at the center of interest and the image at different angles of departure fromr the line of sight connoted by this center.

A preferred instance will now be described in connection with Figs. l and 2.

Letit be assumed that the photograph is to v w be made at an image plane corresponding tor a known visual angle. `This will be true for any constant arrangement of lenses, such as the lens-system described and claimed in my Letters Patent No.`1,482,502, dated February 5, 1921i. Different areas of a sensitive plate exposed in such an image plane will therefore correspond to the respective retinal'surfaces of the eye.

Provision is now made fo'.' maximum chromatic sensitiveness of the plate at a maximum corresponding to the chromatic maximum Lof the fovea centralis in a region near the optical axis of the camera. lens, for instance atv f2, for

decreased chromatic sensitiveness at the immediately surrounding region y2, and for further decreased sensitiveness to the maximum luinniosity color and relatively increased sensitiveness to shorter .wave lengths in a surrounding'zone r2, and finally the remainder of the plate is rendered insensitive to all ei;- cept the shorter wave-lengths for the remain- :der of its surface.

La l These qualities may be imparted to the plate by suitable local treatment of rthe emulsion, butjavpreferred expedient is to influence the color of the image incident upon the plate with screen D.y This screen should, be so devised as to impose no kquantitative absorption, its function being to influence the color only of tlielight transmitted thereby without alter-V ation ofthe uniformity of distribution in a quantitative sense of the light incident upon it. Figs.4 l and 2 illustrate a preferredr construction for this purpose. f The screen is `in two parts, a colored plate d and a corrector ythe plate should thek aid of a suitable. absorption .them when ,they are superposed.

able of suiiicient accuracy of maximum color sensitiveness at the right part of the spectrum, vbutin practice this is'usually attained with thev aid of a color filter or absorption screen, which is generally arranged to exclude some of the light of shorter wave length, in aid of the selective chemical treatment of the film surface ci, the absorption screen generally having the powers of transmission requivalent to a thin film of sodium bichromate or some other yellow dye or stain. The new. screen d is of this nature at the region F, preferably a circular region subtending about one degree ofarc to the nodal point of the lens. The partof the plate f2 under this spot will then Vhave a sensitiveness corresponding to the sensitiveness of the-fovea. v

' The screen cl isalso provided with a region Y preferably an oval about six degrees long and about four degrees wide with re` spect to theY nodal point. This region is colored with'an attenuated dye or pigment permitting more of the shorter wave length light to pass. The surrounding, preferably circular region R of the absorption screen is colored with a still more attenuated dye. The remainder R of the absorption screen may be transparent and uncolored.

It will be observedk that the selective ab@ sorption of the absorption screen d is distributed as it is in the normal human eye, but if such a screen d were interposed alone between the plater and the lens, a substantial part of the quantity of light incident on the plate would be cut off by the regions F, Y, R, of the screen, whereas the illumination of be uniform so far as the function of the absorption screenk is concerned.

Thisis provided for by superposing upon the absorption screenv d thecorrector screen (Z2, which may or may not be colored to infinence the color of thelight transmitted. Forr use with such plates as those mentioned, preferably the corrector screen 'is colored with a neutral pigment. Its central region f corresponding to the spot F may be quite transparent; the surrounding region g/ corresponding-to the spot Y R is more heavily tinted, andthe remainder of the surface r is still more deeply tinted;

, The mutual arrangement of the screens d.

and (Z2 is ysuchasftofcause quantitative uniformity ofV transmission of light through Such screensV may be vmade of any suitable material and by any suitable process. They may be made of glass suitably pigmentedg'or they may bemade ofclearglass having a suitableA is lightlytinted the larger. cireularregion r corresponding to the region with respect pigmented coating; or they-may comprise clear glass enclosing films of gelatine or other transparent colloidal substance locally dyed or pigmented as fdescribed.

Thatever thedetail of thel material employed the distribution ofthe pigment or coloring of the selective screen should substantially correspond in effect upon the transmitted .light tothe variable sensibility of the correspondinfT regions of the retina as explained above.

"When it is desired that the photograph shall aid the impressionof low illumination, the device and method rof'this application maybe employed without change except the .substitution for the screen (Z of a screen of yanother color more absorbent of the red end of the spectrum and less absorbent of the blue end. The eii'ect may be still further enhanced by making the screens for low illumination with less absorptive difference bvetween the central spot andthe yellow spot region Y and the surrounding area R, and thedilference between the region ,R and Vthe region R may be still less in degree. The neutral corrector is correspondingly altered. In general, the photometric density of the various regions of screens may vary among themselves in proportion (to the areas of the appropriate curves shown inFig. 2.

it will be understood that the margins or boundaries between `the differently tinted areas of the components Vof the absorption screen should not be .sharp or hard lines;

tl ese regions merge one into the other ,with

a gradual ditfusion, the complemcntal parts ofthe plates being so merged or diiused in an opposite sense as to maintainuniformity of photometric value of thesuperposed components throughout. i

One construction of screen is illustrated in Fig. 4, in which lthe plate Zsis formed with a central meniscus or countersinlr L .vhich may be of size corresponding to the arealF and circular in outline, or of size and shape correspondingv to thearea Y,'or have Vother suitable shape and size variations interrelated with and.complementary to those of the plate (Z3. A cover plate CZ* may be employed which, if desired, or necessary, may be varied n to compensate for variations in the absorption of plated but preferably is uniformly transparent.

llhe countersink is filled with a ,trans-n parent colored substance having the essen-tial actinic properties to produce the intended result. For example, I may lill the countersinlrwith a button or disc. l ground from yellow or other glass selectively absorbent as respects'the short vwave length end of the spectrum and of substantially thesame index of refraction as plate Zyor with Canada vbalsam Vorother transparent gumor liquid of substantially the same index of refraction as the plate Z3 and havingthe proper transmission 4and absorption properties imparted thereto as by stainingr or commingli'ng absorption elements therewith may be used. The button Z may or may notentirely fill and lit the countersink, and in thelatter case Cana-da balsam or other optical cement ma y be relied upon to iill up Ythe intervalsunite ythe parts, and prevent internal refraction. or

and plated3 isA by fusion, the parts being sub l sequently surfaced. When so joined, there is no visible edge or line of joinder between the parts which might deflect or diffuse impinging light, and the vquantitative transmission of lwhite .light juniform throughout the screen.

I claim: Y l. An absorption screen for use in photography comprising a color absorption element arranged selectively to absorb more light of the same color at one part of the image than at another part of the image, and

acorrector element adapted and arranged to absorb a compensating amount ofthe light transmitted bythe respectiveparts of the absorption screen. 7 2. An absorption screen for use in photography having' a color absorptionelen'ient variable froma central `region of the screen towardits periphery, and a corrector element adapted and arranged for colorless absorption ofL an inversely varying amount of lthe incident light.

3. A color screen for photograpl1y` having a color-absorbing substance arranged thereon in substantially the relative positions and areas` of the fovea'and yellow spot in the normal human eye.

An `absorption screen for use in photography having different powers of absorption of light of different colors in different portions, 4and having thereinineans for compensating vfor vdifferentquantitative translmission of white light on :said portions, whereby itransmitted lllununation Y throughout thescreen ispsubstantially uniform.

5. An absorption screen 'for usev 1n photography including'a member having dit! erent powers of absorption for light pre dominant-ly of one color in different areas,V

lll() iie y 6. A composite absorption screen for use in photography having the property of substan-v tially uniform quantitative transmission of slight, and comprising an absorbent component having areas varying in the property of transmission of selected light Waves.

7. A screen for use in photography adaptedl for uniform transmissions of the same quantity of light throughout rits area and having an element adapted to cause select-ive color absorption progressively varying along any radius of the screen from a central region.

as distinguished from color of the transmitted 20 image.

y Signed by me at Hanover, N. H., this 28th day of May, 1923. y

' ADELBERT AMES, JR. 

